How to Filter Out a Mastodon Hashtag From Your Federated Timeline

The Federated Timeline in Mastodon shows public posts from all instances your server knows. This feed can quickly fill with hashtags you do not want to see. Mastodon provides a built-in filter system to hide posts containing specific hashtags. This article explains how to create a filter that removes a hashtag from your Federated Timeline without muting the entire account.

Filters work silently in the background. Once set, posts matching your filter rules are hidden from every view, including the Federated Timeline. You can apply filters to specific columns or to your entire browsing experience.

This guide covers the exact steps to add a hashtag filter, adjust its scope, and manage existing filters. You will also learn what filters cannot do and how to avoid common mistakes.

How Mastodon Filters Work for Hashtags

Mastodon filters are server-side rules that hide posts based on keywords, phrases, or hashtags. When you create a filter, the server checks every new post against your filter list. If a post contains the filtered hashtag, that post is hidden from the views you selected.

Filters apply to the post content, including alt text and spoiler text. They do not hide posts from your notifications unless you explicitly select the “Notifications” scope. For the Federated Timeline, you must choose the “Public timelines” scope to block the hashtag there.

Each filter can contain multiple keywords or hashtags. You can choose to hide the post entirely or replace it with a warning message that you can click to reveal. Filters are private to your account and do not affect other users.

Prerequisites for Using Filters

You need a Mastodon account on any instance. Filters work the same way on the web interface, official mobile apps, and most third-party clients. You do not need admin privileges or any special permissions.

Filters do not require the exact hashtag format. You can enter the hashtag with or without the # symbol. For example, both “cats” and “#cats” will match the same posts.

Steps to Filter a Hashtag From the Federated Timeline

Follow these steps on the Mastodon web interface. The mobile app uses a similar process but with slightly different button placements.

1. Open Settings
   Click the gear icon in the right column of the web interface. On mobile, tap your profile icon and then tap the gear icon.
2. Go to Filters
   In the left sidebar, click Filters. If you do not see this option, scroll down the sidebar.
3. Click Add new filter
   This button appears at the top of the Filters page. Click it to open the filter creation form.
4. Enter a title for the filter
   Type a name that helps you remember the filter purpose, for example “Block cat posts” or “Hide spoiler hashtag”.
5. Add the hashtag as a keyword
   In the Keywords field, type the hashtag you want to filter. You can enter multiple keywords by pressing Enter after each one. For a single hashtag, type #cats and press Enter.
6. Choose the filter action
   Select Hide entirely to remove the post from your view completely. Select Replace with warning to show a blurred warning that you can click to reveal the post.
7. Set the filter scope
   Check the boxes for Home and Public timelines. The Public timelines scope covers the Federated Timeline and the Local Timeline. Do not check Notifications unless you also want to hide the hashtag from your notification column.
8. Set expiration (optional)
   You can leave the filter active forever by not setting an expiration. To make the filter expire after a set time, click Expire and choose a date and time.
9. Click Save
   The filter is now active. Any new post containing the hashtag will be hidden from your Federated Timeline.

Existing posts that were already in your timeline are not retroactively hidden. Only posts that arrive after you save the filter are affected.

Common Mistakes and Limitations With Mastodon Filters

Filter Not Hiding Posts From Federated Timeline

If a post with the filtered hashtag still appears, the filter scope is likely set incorrectly. Go to Settings > Filters, click the filter name, and verify that Public timelines is checked. If only Home is checked, the filter applies only to your Home feed, not the Federated Timeline.

Filtered Hashtag Still Shows in Search Results

Filters do not hide posts from the Search column. If you search for the filtered hashtag directly, the matching posts will appear. This is by design so you can still find content intentionally.

Filter Not Working on Mobile Apps

Filters set on the web interface sync to the official Mastodon mobile app automatically. If the filter does not appear on mobile, force close the app and reopen it. Third-party clients may not support all filter features.

Mastodon Filter vs Mute vs Block for Hashtags

Item	Filter	Mute Account	Block Account
Scope	Specific hashtag across all accounts	All posts from one account	All posts from one account
Effect on Federated Timeline	Hides posts with the hashtag	Hides all posts from that account	Hides all posts from that account
Effect on Notifications	Only if scope includes Notifications	Hides notifications from that account	Prevents the account from following you
Retroactive	No	Yes	Yes

Use a filter when you want to remove a specific hashtag from your timelines without affecting the accounts that post it. Use mute when you want to stop seeing all content from a specific account. Use block when you want to prevent an account from interacting with you entirely.

You can now filter out unwanted hashtags from your Federated Timeline using the steps above. Try adding a filter for a hashtag that frequently appears in your feed. For advanced use, combine multiple keywords in one filter to block several related hashtags at once. Remember that filters do not hide posts from search results, so you can still find content deliberately when needed.